Add sudoku validity holesky address as env var

.env.template

@@ -2,8 +2,9 @@ ETH_CHAIN=<devnet/holesky>
 MINA_RPC_URL=<url>
 SAVE_PROOF=true/false # also false if other than "true" or variable were to be not defined
 
-## A Mina fee payer account is needed for running the Sudoku example
-#FEEPAYER_KEY=<private_key>
+## These are necessary for running the Sudoku example
+#FEEPAYER_KEY=<mina_private_key>
+#SUDOKU_VALIDITY_HOLESKY_ADDRESS=<contract_addr>
 
 ## These can be skipped if using devnet with Anvil.
 # BATCHER_ADDR=<optional>

example/app/src/main.rs

@@ -21,7 +21,6 @@ use std::{process, str::FromStr, time::SystemTime};
 
 const MINA_ZKAPP_ADDRESS: &str = "B62qmpq1JBejZYDQrZwASPRM5oLXW346WoXgbApVf5HJZXMWFPWFPuA";
 const SUDOKU_VALIDITY_DEVNET_ADDRESS: &str = "0xb19b36b1456E65E3A6D514D3F715f204BD59f431";
-const SUDOKU_VALIDITY_HOLESKY_ADDRESS: &str = "0xeAB6068E1e06941A9d47734FB49C3B9dD69E054d";
 
 sol!(
     #[allow(clippy::too_many_arguments)]
@@ -186,7 +185,12 @@ async fn main() {
             debug!("Creating contract instance");
             let sudoku_address = match chain {
                 Chain::Devnet => SUDOKU_VALIDITY_DEVNET_ADDRESS,
-                Chain::Holesky => SUDOKU_VALIDITY_HOLESKY_ADDRESS,
+                Chain::Holesky => {
+                    &std::env::var("SUDOKU_VALIDITY_HOLESKY_ADDRESS").unwrap_or_else(|err| {
+                        error!("Could not read SUDOKU_VALIDITY_HOLESKY_ADDRESS env var: {err}");
+                        process::exit(1);
+                    })
+                }
                 _ => todo!(),
             };
             let contract =